As a recording media with high-speed, sufficient capacity, strong reliability and low cost, disk drives are widely used for digital information recording. After the technology development for many years, the recording density of a disk drive has been developed to exceed 100 GB per square inch. The disk drive includes a slider incorporating a thin film head for recording and reproducing data information stored in a recording media. The slider has a surface facing to the recording media which is referred as air bearing surface (ABS).
For an MR element (magneto-resistive element, MR element) which reads information from the recording media, it is important to maintain height of the MR element (the height measured vertically from the ABS to the MR element) to its design value for ensuring reading performance of the MR element.
Because the height of MR element is obtained by lapping the ABS firstly, then removing the rest of the MR element, in process of depositing an MR element which has an original height larger than it's design value on a wafer, it is important to maintain the precision of lapping clearance of the ABS and thus maintaining the precision of the MR element height.
Further, it is important for an inductive magnetic element which writes information to the recording medium to make the throat height (the height of two opposing poles used for writing operation measured vertically from the ABS) as its design value. It is also important to maintain the precision of lapping clearance of the ABS, since the throat height is also attained by lapping the ABS.
However, because the lapping surface is disposed in a vertical direction with respect to a wafer surface which is formed two-dimensionally by pluralities of sliders, the wafer need to be sliced in advance in lapping processing so as to expose the lapping surface. Therefore, it is necessary to cut the wafer along a direction at which the lapping surface is disposed into a plurality of row bars formed by an array of sliders, and the lapping surface is lapped together with the row bar (further dicing the row bar into individual sliders and lapping in slider level is low efficient and therefore is unpractical). The row bar is supported by a predetermined fixture, then pressed onto a revolving lapping table and lapped, as disclosed in U.S. Pat. No. 5,607,340 and U.S. Pat. No. 5,620,356.
In lapping process of the row bar, it is very important to maintain not only the clearance precision of each part which form an entire slider, but also that of the whole row bar, i.e., it is critical to grind evenly the whole row bar for ensuring it's flatness.
However, in row bar lapping process using conventional technology, as the press force applied to the row bar is distributed unevenly along the longitudinal direction of the row bar, thus lapping clearance deviation is produced along longitudinal direction. Accordingly, problems arise, such as MR element height or throat height of a slider thus formed can not get its designed value and product yield of non-defective sliders decreases. One reason lies in: in fact the contour of the lapping surface of row bar should be approximately a curve of at least sixth order with respect to longitudinal direction of the row bar, while conventional row bar supporting method can simulate only curve of fourth order at most, and thus will result in low product yield, as disclosed in JP patent publication NO. 2000-11315. Therefore, a method for improving contour control freedom of the lapping surface is disclosed as follow: deforming freedom exists on a load applying member used for applying load to a row bar not only at direction toward which the row bar is pressed, but also along longitudinal direction and rotation direction of the row bar for improving control freedom, as disclosed in JP patent application NO. 3,537,726.
FIG. 8 shows a side view of a conventional fixture used in a lapping process. The lapping fixture 150 comprises a main body 151, a holding body 152 used for retaining the row bar (not shown), and a plurality of connection members 153a–153d (four connection members are shown in the figure) which connect the main body 151 and holding body 152. The row bar is secured to a row bar securing portion 158 formed at the front end of the holding body 152. In addition, the lapping fixture 150 further comprises a plurality of load-applied members 154a–154g for pressing the holding body to a revolving lapping table (not shown). The load-applied members 154a–154g are kept tight contact with the revolving lapping table by a plurality of load applying components which are inserted through holes of the load-applied members 154a–154g respectively, and then the row bar mounted on the row bar securing portion 158 is lapped. The lapping fixture 150 further comprises attaching holes 156, and matching portions 157a and 157b used for supporting the lapping fixture 150. A fixing pin (not shown) is inserted through the hole 156 and the lapping fixture 150 is mounted to a lapping device. Each of the matching portions 157a and 157b has a guide pin (not shown) inserted therethrough and the excessive displacement of the main body 151 is prevented from happening by mutual engagement formed between the matching portions 157a, 157b and guide pins.